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SPECIAL REPORT 



OP THE 



STATE ENTOMOLOGIST 



OF 



MINNESOTA 



TO THE GOVERNOR 



THE MEDITEERANEAN ELOUR MOTH 



FEBRUARY 29, 1904 



AGRICULTURAL EXPERIMENT STATION, 

ST. ANTHONY PARK, MINN. 






JUL io 1904 
D, of D, 



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EDITH REED, DEL. ET PINX. 



ft. HOEN 4 CO., LITH., BALTO., MD. 



THE MEDITERRANEAN FLOUR MOTH. 



THE MEDITERRANEAN FLOUR MOTH 

El^hcsfio kiicJiiiicIld, Zcll. 



His E.vccHcJicy, S. R. J\vi Saiit: 

Many millers arc asking' for information as to how to rid 
their mills of this much dreatled pest, which has recentl}' ap- 
peared in alarming numbers in this vicinity, apparently for 
the first time. 1 say a])parently, for, altiiough there is no 
record until the present time, of its ])resence near here, we 
have reason to believe that it has from time to time appeared 
in various parts of th.e state. Naturally if a mill is infested, 
the matter is not discussed, and this fact makes an outbreak 
all the more serious, for no pest calls more for co-o])eration in 
combating-, and more general consultation and comparison 
of results of different treatments than the Mediterranean 
Flour Moth. The millers have every reason to dread this 
insect, since it sometimes completely stops the machinery of 
a Hour mill, and w hen ])resent alwa^'s calls, sooner or later, for 
the expenditure of much effort and much money before a mill 
can be free from its de])redations. 

The fact that a mill is new is no safe-guard against con- 
tamination from returrie<l sacks or the introduction of eggs of 
the pest in secondhand machinery coming from an infested 
mill. Nor is a clean mill exempt f»ir the same reason, though 
regular cleanings have much to do with checking; its increase. 

In view of the seriousness of the situation and the lack 
of definite informati(jn u])on this sul)iect among man_\' of our 
luillers, who do not know the best means of fighting the moth, 
and in consideration of the fact that it is a pest which may 
ap]3ear sooner or later in any Hour mill, the entomologist has. 
felt justified in issuing at this time a special report upon the 
Flour Moth, fully illustrated, giving its life history, habits, and 



2 THE MEDITERRANEAN FLOUR MOTH. 

chief sources of infection, the best renie(Hes and means of pre- 
vention. Copies of this report will be mailed to all millers 
in .Minnesota. 

My predecessor. Dr. Lugger, had never included this pest 
in any of his bulletins. In April, 1900, he printed in the 
Northwestern Miller a popular account of the insect, with 
illustrations. In this article he advised fumigation with bi- 
sulphide of carbon, a process which millers do not apparently 
find satisfacttjr}'. Since that time considerable advance has 
been made in our knowledge of methods of control, which the 
l)resent report aims to place before the millers of the North- 
west. There ha\'e been some ex])eriments on the part of the 
entomologist bearing upon the effect upon the insect and 
its eggs of exposure to certain temperatures for a definite 
length of time, upon the effect of liquid bisulphide of carbon, 
and of the gas, upon the eggs, and upon the effects upon the 
larvae of exposure to a known volume of the gas of C. S^; for 
a definite time. The colored plate, excellently true to life, 
V\'as made under the writer's direction, from actual specimens, 
as were the original photographs which appear in tlie body of 
the re]wrt. ddie best remedial and preventive measures have 
been (detained by recent interviews with practical millers, who 
have used said measures successfully, the writer taking the 
liberty to make certain suggestions as the result of some per- 
sonal observations and knowdedge of the insect's habits. It 
has seemed desirable also to ai:)]K"nd short descriptions of 
some other pests found in fiour mills and granaries, most or 
all of which, when found in mills, are killed by the same treat- 
ment wdiich has been found effectual against the fiour moth. 



Description of Moth, Larvae and Egg; Its Life, History and 

Habits. 

This moth, named Ephcstia kiichiiiclla, by Professor Zeller in 
1879 in honor of Professor Kuhn of the University of Halle, 
(iermany. is from 2/5 to 3/5 of an inch long, measuring 
from 3/5 of an inch to i inch from tip to tip of expanded 
wings. Its general color, wdien freshly emerged from pupa, 



THE MEDITERRANEAN FLOUR MOTH. 3 

is blackish gray, the frcMit wings being grav, spotted with 
black scales, and irregular, angular black lines crossing 
the wing- near the tips. A characteristic W shaped black 
line will be noted crossing the wing about half way be- 
tween the tip and liase ; see colored plate. Fig. i repre- 
sents the moth enlarged three times. Fig. 2, the larva 
which produces the moth, also three times enlarged; Fig. 3, 
the pui)a found in the cocoon, same enlargement; Fig. 4, the 
head and anterior segments of the larva to show details, en- 
larged six times; V\cr -_ the posterior segments to show de- 




l^ig- 1.— Mediterranean Flour .Moth, three and three-fourths times enlarged. Original, 

tails, enlarged six times; Fig. 6, the dorsal view of. head and 
thoracic segments, showing- details of shield, enlarged six 
times ; Fig. 7, abdominal foot, twelve times enlarged, showing 
crown of hooks; Fig. 8, freshly made cocoon, formed in flour, 
showing larva within, three times enlarged ; Fig. 9, one fore 
wing, showing venation, six times enlarged; Fig. 10, a hind 
wing, showing venation, six times enlarged ; Fig. 11, a freshlv 
laid e^g, enlarged tw^enty-five times. The hind wdngs are 
thin, translucent and silvery. Both fore and hind wings are 
heavily fringed. All the above figures refer to the colored 
plate, not to the illustrations in text. 



4 THE MEDITERRANEAN FLOUR MOTH. 

The females are a little larger than the males, but the col- 
oration of the wings of both sexes is alike. The females have 
a characteristic habit, upon emerging from the pui)a, of re- 
maining for hours with tip of abdomen and head raised above 
the level of the rest of the body ; see Fig. lo. Egg laying, 
which lasts several days, takes place, as a rule, immediately 
after copulation, each female averaging about 200 eggs. These 
eggs mav be placed anywhere, in cracks, in flour, in spouts, 
purifiers or other machinery, in sacks containing riour or 
meal, in any place, in fact, to which the moth has access. 




Fig. 2.— Larvae cjf Meditci ranean Flour Moth, four limes enlarged. Original. 



The lan'a, sometimes called "the worm" (see colored i)late,. 
also iMgs. 2 and 10 in the text), is about 1/2^ of an inch wlicn 
first hatched, from white to pink in color, with a reddish 
ijrown head : a few very small hairs are scattered oxer the 
b(jdy. The larval life is about h^'ty days, and when full 
grown it measures from I 2 to 35 of an inch in length. 'Idie 
color becomes more pronouncedly pink than in the young 
larva. We have noted in the laboratory that individuals vary 
in color, some even appearing to have a greenish tint. There 
are six true legs near the anterior end of the body, and four 



THE MEDITERRANEAN FLOUR MOTH. 5 

pairs of rather long fleshy legs on the ahdomcn. With a 
lense one can see that each one of these abdominal legs is 
provided with a circle of small hooks at the end (Fig. 7, col- 
ored plate). Idiere is also a pair of so-called caudal legs at 
the extreme posterior end of the larva. 

Little blackish or brownish spots, each bearing one or two 
hairs, are formed over the body, three on a side in each seg- 
ment. At the anterior and posterior ends, the spots which 
are lower down on the side are larger and more conspicuous 
than the others. ( )ne spot on each side, just back of the head, 
is formed by an incomplete ring, its circumference being 
broken toward the head. A careful study of the colored plate 
(Figs. 4 and 5). will help one in recognizing these details. 
Just l)ack of the head (see Fig. 6 of colored plate), is a con- 
spicuous rcvldish ])r(nvn plate or sliield, divided into two parts 
by a middle pale line. 

The larva has a pernicious habit of secreting a silken 
thread where\ er it goes. A\'hen traveling back and forth 
o\er a smooth surface this results in a sheet of silken tissue 
of consideraljle strength, much like that seen in b'ig. 6 in 
text, which illustrates the work of the worms on a piece of 
bolting cloth coxering a breeding jar in our laboratory. When, 
howe\er, the larvae are crawling through flour or meal the 
result is, as many millers know to their cost, a mass of flour 
held together by countless threads, forming a webbing which 
clogs spouts, ele\ator le^s and either machinery to such an 
extent frefjuently ?s tij completely stop the work of the mill. 
(See Fig. 5 in text. ) 

77//.V larva may find Its i^'oy into a perfectly clean mill in re- 
turned sacks, unless said sacks are treated in some wax before 
being placed in mill. Secoiut-hand machinery from an infested 
iiiill may harbor larvae or eggs. When full grown, which takes, 
as \ve have said, about forty da'ys, the larva crawls about rest- 
lessly until it finds a place to sj^in its cocoon, about 1/2 inch 
long, within which it transforms to a pupa ( Fig. 8 of colored 
plate; see also b of Fig. 10). If this cocoon is spun in flour 
or meal it is matted with the fine particles, as shown in the 
colored plate. (See also F"ig. 4 in text of report.) The pupa 
is reddisbi l)rown, a little less than 1/2 inch long, and about 



6 THE MEDITERRANEAN FLOUR MOTH. 

1, lo of an inch wide. The last seg^nient of the body of the 
pupa is provided with a few .short liairs. Tlie length of the 
pupal sta,s^e within the cocoon is evidently from ten to twelve 
days. 

The time elapsing between laying- of egg, hatching of same 
and transformation of larva into a pupa, and the emergence 
of the moth, is evidently between sixty and seventy days, or 
an average of nine weeks for one generation. 




Fig. 3. — Egg of Mediterranean I'^Dur Moth, fifty times enlarged. O'-iginal. 



The (;i,'"_i,^ oval in shajjc, when first laid white and almost 
smooth, later becoming brownish and wrinkled, is just visible 
to the naked eye. The eggs hatch in nine or ten days. Two 
freslily laid eggs, measured in the laboratory, were each .6 
millimeters long by .35 millimeters broad, or about 1/42 of 
an inch long by i/^>3 of an inch broad. We figure one of 
these enlarged twentv-fi\e times on colored plate (Fig. 11). 
Also same egg in text. Fig. 3, enlarged fifty times. 

/:\i.[,i;\s-, as zccll as larz'ac. may be brdiijj^ht into a l^crfcctly clean 
mill in i)ifcstccl material, thus sowing the seed of trouMe: sacks, 
barrels, and second-hand n;achinery from S(mie infested mdl being 
the chief sources. 

( )ne female which we had under observation in the labo- 
ratory at St. Anthony l^ark began egg laying February 9th, 
continuing until and including February 14th, five days, lading 
during that period 247 eggs. Copulation lasts a long time and 
evidently one female may mate with several males, laying 
eggs l)etween the dififerent matings. 



THE IMEDITKRRANEAN FLOUR MOTH, 7 

As regards the food liabits of this insect ; rice Hour is a 
dainty dish for the larvae, as is flour made from buckwheat. 
Any infested mill which keeps flour in sacks before shi]:)ping 
may hear sooner or later from the consumer or retailer that 
'"the flour is wormy." This is caused by the female moth 
pushing her ovipositor through the sack and laying her eggs 
in the flour inside. Crackers, germea, rolled vvheat, oatmeal 
and corn meal are all said to suffer. 

The moth is evidently a continuous breeder in warm local- 
ities, in warm mills for instance. It is a well known fact that 
cold retards and warmth hastens its developiuent, luillers 
sometimes taking advantage of the first point to keep the pest 
in check. 




\-ig. 4. — <;. cocoon from beluw showing pupa tlirough the 'thin silk attaching cocoon 
to some surface: h. same from above, enlarged — Riley & Howard in Insect Life. 



Dr. Fletcher of Canada, says in connection with the out- 
break there, that there are probably two normal broods, one 
in the spring, another in the autumn, but he thinks he raised 
as many as three distinct 1>roods in a warm room during the 
winter. F. H. Chittenden, of Washington, claims that in the 
warmest weatlier in that locality, the life cycle occupies only 
five weeks. Prof. \\\ G. Johnson states, in C(^ntradiction to 
Mr. Chittenden's experience, that he has been unaljle to get a 



8 THE xMEDlTERRANEAN FLOUR MOTH. 

full grown larva in less than five weeks from the time it 
emerged from the egg. 

Preventive Measures. 

Clco'iliiicss: 

Because a mill is clean or new is no reason why the moth 
cannot be introduced, if sacks containing eggs or larvae, or 
second-hand machinery from an infested mill are allowed to 
enter. At the same time, scrupulous cleanliness has much to 
do with immunity, for eggs and larvae are dislodged by pro- 
cesses involved in the term, and not allowed to develop. 




Fig. 



-I'lour niatU'd together by web spun by larvae, one-half natural size. — Lugger. 



Every mill, it would seem, should, and many do, have cleaners 
or sweepers, whose sole duty it is to see that every floor and 
all machinery, purifiers, spouts and elevators are kept clean. 
Naturally such an employe or employes should have some 
knowdedge of insects found in Houring mills. 

Fiiniigation House: 

The writer is convinced, from talking with millers who 
have had experience with this pest, that the chief source of 
contagion lies in receiving into the mill returned sacks, and 
also second-hand machinery from an infested mill, which may 



THE MEDITERRANEAN FLOUR MOTH. 9 

harbor the eggs or larvae. Some mills, in order to avoid in- 
fection, will not take back old sacks. If a milling company- 
must do this such material should be thoroughly treated before 
being allozced in the ntill. A fumigation house, or room, might 
be constructed, wdiere sacks or machinery could be fumigated. 
If sacks have been in transit for more than nine days, and 
during that time free from all sources of contagion, all eggs 
which may have been originally in the package have hatched, 
hence, one need not seek for a treatment which will kill them 
(the eggs), but only for such as will kill the worms which 
have hatched from the eggs. Carbon bisulphide is the best 
and safest fumigating material at our disposal, and could be 
well used in this instance. The gas generated by this liquid, 
when mixed with air, is highly explosive, and no lighted match 
or lamp, or lighted cigar or pipe should be brought near it. As 
it is definitely known just how much of this liquid is required 
to create a "death atmosphere," the cubical contents of this 
room, or better, house, should be accurately determined. 
From experiments tried with this gas by the writer, he would 
suggest one part of liquid for every one thousand parts of at- 
mosphere. To determine, if possible, whether this strength 
of gas would penetrate to the center of the bale in killing 
quantity, the entomologist inclosed "worms," pupae, and 
moths in vials loosely stoppered with cotton. These vials 
were placed in a flour sack, which was tightly rolled up. This 
bundle was placed in a second flour sack, which in turn was 
tightly rolled, and the package placed in a burlap sack and 
rolled again. This compact bundle with the worms in the 
very center was then exposed for three days, in a tight iron 
box, to fumes of carbon bisulphide, one part of the liquid to 
I, GOO parts of atmosphere. This killed every "worm," 
pupa and moth. The fumigation house or room must 
be absolutely tight to retain the gas. The liquid should be 
placed in shallow trays, and the room closed for at least 
three days if the sacks are left in the bale. A longer time 
than that, under such conditions, would be highly desirable. 
If the worm cannot be reached in the bale by fumigation for 
three or five davs with the above strength, millers should be 



10 THE MEDITERRANEAN FLOUR MOTH. 

willing to open up the bales. This involves extra handling, 
and means added expense, but might be an imperative neces- 
sity, for tvork not thoroughly done in this connection represents time 
and money thrown atcay. After fumigation the house or room 
should be thoroughly aired before allowing a light of any kind 
inside. 




Fig. ij. — Silk felt spun by larvae in crawling across bolting cloth on top of breeding 
jar; showing also larvae, pupa cocoons and moths somewhat reduced. Original. 



The gas from bisulphide of carbon will sink through a 
mass of wheat in a large bin, and also through a chestful of 
woolen clothing, if in each case the liquid is placed in shal- 
low dishes on tcjp of the wheat, or clothing. It is probable, 
therefore, that it wdl penetrate a loose bale of sacks. Possibly 
heat alone might be profitably used in this connection. 



THE MEDITERRANEAN FLOUR MOTH. 



11 




Cyliiidrical Metal Spouts: 

L. C. Schroeder of Olean, N. Y., has in- 
vented and patented a metal spout, shown in 
Fig. 7, which is reported as giving satisfaction, 
since it presents a smooth surface within, and 
no corners, thus being a great improvement, 
as regards the flour moth, over the wooden 
spouts which aiTord such an excellent oppor- 
tunity for the larvae and the laying of eggs. 
It is claimed that the metal spouts cost less 
than those made of wood. This principle, for 
reasons which will at once be obvious to prac- 
tical mill men, cannot well be applied to the 
elevator legs, although it is said that the same 
party has patented a metal elevator leg. 

Belt Brushes: 

Since metal elevators cannot be economic- 
— Adjusta- ally introduced into our mills as they are now 

ble metal spout. — j. j. i 11 ^ j • r 1 

From w. G. John- Constructed, an excellent device for keeping 
eport. ^1^^ wooden elevators clean, if we are to be- 

lieve statements of those who have used them, consists of 
an elevator brush as shown in Fig. 8, constructed as follows: 

"To make the brush, take a 
piece of i 1/2-inch plank of the 
same dimensions as the elevator 
cups, and fasten bristles to three 
sides. The side A is fastened to 
the elevator belt with flat-headed 
JD bolts running through the plank, 
as shown at B, B, the bolts being 
1/4 or 3/8 of an inch. The bris- 
tles on the sides C, C, should be 
3/4 of an inch long, but those at 
D should be longer, so that they 
will give a good brushing to the 

The 
brush is easily made, and the mil- 
ler can make it of any size to fit his elevators." 



yf 




C 

Fig. 8.--Elevator Brush.-From W. outer sidc of the clcvator. 
G. Johnson s Report. 



12 THE MEDITERRANEAN FLOUR MOTH. 

Co-opcratioii: 

Co-operation on the part of all millers, particularly where 
mills are in the same district, seems absolutely necessary. If 
one fumigates returned sacks, and goes to the expense of 
freeing his mill of this pest, all should. Otherwise, moths 
from the untreated mills are almost sure to enter a cleaned 
mill, rendering the work of the more careful miller, in this 
connection, of little value. Screening windows and doors 
might be resorted to, and form at least a partial protection, 
though occasioning additional expense. Observations at the 
Experiment Station indicate that the moth cannot pass 
through the mesh of ordinary wire mosquito netting (144 
meshes to the square inch.) 

Freezing: 

This most excellent and inexpensive method is available 
for Minnesota millers during almost any winter. The spouts, 
elevator legs, purifiers and all machinery should be first 
freed from masses of webbed flour, etc., left open (this does 
not mean the unscrewing of the sides of the elevator legs or 
spouts), and then all windows thrown open for a period of 
four or five days, after which windows should be closed and 
heat turned on. The importance of exposure to heat after 
the freezing must not be underestimated. The owners of 
one infested mill stopped their machinery this winter, opened 
all machines, spouts and elevators to allow access of cold 
air, and then kept their windows open for a period of four 
days. This was done in a time of extremely severe weather, 
the thermometer ranging at the time from ten degrees be- 
low zero to thirty-two degrees below, the average tempera- 
ture of the mill during that period being 5 degrees below 
zero. At the expiration of this period windows were closed 
and heat turned on. Some larvae ("worms") and moths col- 
lected, and subjected to examination for several days, did not 
revive, killed by the extreme cold, aided possibly by the sud- 
den change from warm to cold and cold to warm. Eggs sub- 
jected to the above freezing, and kept under observation for 
fifteen days and over, did not hatch ; nor did the weevils, and 



THE MEDITERRANEAN FLOUR MOTH. 13 

other pests found with the Flour Moth, survive this treat- 
ment. These statements were made to the writer ; they are 
not his observations. 

However, while millers in Minnesota can secure at some 
time, during almost any winter, a temperature sufficiently 
low to kill by freezing, yet such a condition is not always 
present, even in Minnesota, when wanted (if outbreak occurs 
in early spring and summer for instance), and surely millers 
in the South could rarely, if ever, take advantage of this 
method. The bisulphide method (not fumigation) must of 
necessity have to be resorted to, when temperature conditions 
are not favorable for freezing. 

In one or two mills subjected to this freezing process fire 
had to be kept in the basement, and a sufficiently low temper- 
ature could not be secured, the treatment in consequence 
resulting unsatisfactorily. See also results of experiments by 
the entomologist on page 14. In one mill, however, where 
the entire mill was exposed to severe cold for eight days or 
more, the process was an absolute success. 

Observations and Results of Experiments by the 
Entomologist. 

In the short time between the report of the recent out- 
break of this moth and the placing of copy in the hands of 
the printer, the entomological department has been able to 
make some observations and try a few experiments in con- 
nection with its extermination, the results of which are here 
given. 

Mating and egg laying: time elapsing bctzveen laying of egg and hatch- 
ing of same. 

Pairing is evidently protracted, one isolated pair under observation 
remaining in copula four days. Ovipositing in one case lasted six days, 
a female beginning egg laying on February 9th and continuing until the 
15th, on which date she died. During this time the one female laid 247 
eggs. These eggs began hatching on the i8th, nine days after the first 
were laid, a recording thermometer registering an average temperature 
of 70 degrees Fahr. in the room during that time. Two freshly laid 
eggs were measured, each measuring .6 millimeters in length by .35 
millimeters in breadth, or, in round numbers, 1/42 of an inch long by 
1/63 of an inch in breadth. 



14 



THE MEDITERRANEAN FLOUR MOTH. 



The night of the Moth: The question as to whether moths would fly 
from one mill to another suggested observations along this line. The 
insects if left to themselves did not fly in the morning. Late in the 
afternoon and in the evening after the light was turned on, an assistant 
reports them flying freely across the room, although not attracted to 
the lights, but rather avoiding them. Observations elsewhere indicate 
that they will fly at least no feet, and probably farther. 

Can the Moth get through zvire mosquito netting f Moths confined for 
several days in a cage made of wire netting, 144 meshes to the square 
inch, did not escape, dying within the cage. 

Effect of liquid Carbon Bisulphide on eggs, larz'cc, pupce and moths: One 
contact for a few seconds with this liquid killed eggs, young and full- 
grown larvae and moths. The pup^e were not killed immediately, but 
died later. 

Effect of vapor of Bisulphide of Carbon on egg: Eggs exposed directly 
to this gas for a few hours did not hatch. 

Effect of knotvn low temperature on the eggs: Experiment in progress 
when this report goes to press. 



Least z'ohwic of Carbon Bisulphide (CSi) and least time of exposure 
necessary to kill full-groii'n larz'cc and moths by fumigation: 



Condition of Insect. 



Full-grown larvae 



Full-grown larvae 

Full-grown larvae 
and moth 



Full-grown larvae 
and moth 



vStrength of Gas. 



I Part liquid CS2 to 1,500 parts 
atmosphere 

I Part CS2 to 3,000 parts atmos- 
phere 

I Part CS2 to 6,000 parts atmos- 
phere 

I Part CS^ to 12,000 parts atmos- 
phere 



Time Exposed. 



I hr. 4omin. 

1 hr. 

2 hrs. 

3 hrs. 



Results. 



Killed. 
Killed. 
Killed. 
Killed. 



Effect of exposure of moths, eggs, larvce and pupce to known lozv tem- 
peratures for definite lengths of time. 

Lot No. I. Exposed out of doors in breeding jar, for three days, to a 
temperature ranging from 18 degrees above to 12 de- 
grees below zero. All killed. 

Lot No. 2. Placed in cold storage at 32 degrees for four days. Living 
at expiration of that time. 

Lot No. 3. Placed in cold storage at 14 degrees above zero for four 
days. A few worms survived. 



THE MEDITERRANEAN FLOUR MOTK. 15 

Lot No. 4. Placed in cold storage at 6 degrees for four days. One or 

two "worms" survived. 
Lot No. 5. Placed in cold storage at i degree above zero for four 

days. All killed. 
Lot No. 6. Placed out of doors for four days, temperature ranging 

from 18 above to 21 below zero. One or two worms 

survived. 

It would seem, then, from the above, and from the experience of 
millers cited on page 13, that the "freezing process" to be thoroughly 
effective must be most thorough. Mills should be so constructed that 
all water pipes can be emptied, allowing all parts of the mill to get 
extremely cold. Further, since we know that a long continued even 
cold temperature is not always fatal to insects (note the hibernation 
of Minnesota insects, for example), but that exposure to cold and 
thawing alternately is fatal, we would suggest that millers in this work 
arrange to alternate the extremely cold temperature with warm, that is, 
after the first exposure to cold for a few days, allow the mill to become 
warm and follow this with another cold exposure. The above lots, Nos. 
I to 6, were masses of matted flour containing the worms, the latter 
being thus somewhat protected. 

Spraying with Bisulphide of Carbon. 

This method, wliich has been very successfully practiced, 
consists in forcing the Hquid by a syringe made for the pur- 
pose into all the machinery infested, inside of spouts, etc. 
Parts of the mill or fittings which do not come in cc^ntact 
with grain or products made from same can be well treated 
with kerosene, squirting it into cracks between joists, and 
into cracks between joists and iron braces, into cracks about 
windows, along baseboards, and into cracks in floor, walls 
and ceilings. It is evident that this must be done most thor- 
otighly to reach all eggs or worms concealed in such places. 
Fig. 9 represents a syringe itsed for spraying the bisulphide 
or kerosene. It may be made of iron pipe, of brass, or of tin. 
It is eighteen inches long, two inches in diameter, and will 
hold, at those measurements, about one quart. The rose 
is detachable, unscrewing from the barrel, and it (the rose) 
is filled on the end with many very small holes, as small as 
the finest needle, in order that the liquid may not be wasted. 
In filling the syringe the rose can be unscrewed and the end 
of the syringe immersed in the can holding the bisidphide, 
or, and this is much better, a little screw cap, not shown in 
the illustration, mav be made on the side of the rose and the 



16 



THE MEDITERRANEAN FLOUR MOTH. 




liquid drawn in through that. This is by far the best plan, 
for when the rose is unscrewed and the liquid drawn into 
the syringe it necessitates the holding of the filled barrel up- 
right in order to screw on the rose, under which circum- 
stances the liquid will run out below, near the handle, unless 
the piston rod fits very snugly. 

When the syringe is used with kerosene, the rose is 
unscrewed and a small nozzle with one aperture, con- 
siderably larger than the holes in the rose, put on in 
its place. This is used when treating cracks in 
lioors, etc. 

Before the work with carbon bisulphide or with 
kerosene is begun, elevator legs, spouts, purifiers and 
all infested machinery must be thoroughly cleaned, in 
other words freed from all matted flour. When the 
spouts are lined with tin. affording a retreat for the 
worms beneath the tin, the wooden sides must be 
removed to get at the culprits. Swabs of cotton waste 
or pieces of old sacks should be run through the eleva- 
tors (stuffing these swabs into cups), takmg off caps 
of elevators and having men, stationed at the top, take 
out the ascending swabs when they reach them, and 
put in other swabs in the descending leg. The eleva- 
tor brush. Fig. 8, might be well used in this connection, or 
brushes made from the same material as the belting, frayed 
on three sides and riveted to cups. All conveyors should be 
taken out and thoroughly cleaned. Purifiers and reels and 
insides of conveyor boxes, all machinery in fact, should be 
thorough!}' si)rayed with carbon bisulphide after having been 
cleaned. The cloth tubes on dust machines should be burned. 
In treating elevator legs with carbon bisulphide, the same 
method can be used as in cleaning, described above, saturat- 
ing the swabs with the liquid. A swab should take up about 
one pint of the liquid. 

All this means the expenditure of time, and monev for 
material. An ordinary sized mill may, in this process, use 
from i,ooo to 1,500 pounds of carbon bisulphide, or even more, 
to say nothing of the large amount of kerosene employed. 
We are reliably informed that bisulphide of carbon can be 



Fig. 9. 



THE MEDITERRANEAN FLOUR MOTH. 17 

purchased for 6 1/2 cents per pound of a dealer in New York 
City and St. Louis. This price does not include container, 
credit for which is allowed upon its return. 

Caution: The gas generated by bisulphide of carbon is 
inflammable. Therefore, while it is being used and until the 
mill has been thoroughly aired after treatment, no light of 
any kind should be allowed in the mill. A lighted cigar or 
pipe, lantern, or lighted match, if brought into the mill when 
filled with gas might cause an explosion. 

Effect of the Gas on Human Beings. This liquid can be 
safely handled by workmen in the mill if they will take the 
precaution to go at once into the open air when they feel 
any bad effects from inhaling the gas. The mill, during this 
process, should be tightly closed to make the work more ef- 
fective, and in consequence is filled with fumes. If these 
fumes are inhaled by the men for some length of time with- 
out the precaution above mentioned of going frequently to 
the fresh air, temporary nausea and sickness may result, 
while prolonged exposure to dense fumes in a tight room 
might result very seriously. Nature, however, gives one 
warning in plenty of time to avoid danger. Then, too, in a 
case which came under the writer's observation, men working 
with the stuff became more or less immune, and one indi- 
vidual was hardly affected at all. 

As is evident, the treatment of a mill in this way should 
be in charge of a reliable and competent man of intelligence, 
one fully posted as to the nature of the chemical his men 
are handling. 

Methods Which Have Been Tried and Found Ineffective or 
Less Desirable than the Preceding. 

Fumigation zcith Bisulphide of Carbon : Although this has 
been the common practice in the past, and is generally rec- 
ommended in cases of attack of this insect, actual experience 
with its use does not bear out the recommendation, in that it 
does not appear to kill the moths or worms under the condi- 
tions which prevail in almost every mill. It may be effective 
against other insect pests with which flour mills are troubled, 



18 THE MEDITERRANEAN FLOUR MOTH. 

thus giving rise, from published report, that it is effective 
also against the Mediterranean Flour Moth, but we know 
of at least three instances where it was tried in large mills 
and proved valueless. 

The process consists in placing pans of carbon bisulphide 
on the different floors, using a definite amount of the liquid 
(about one part to every one thousand parts of atmosphere), 
first making the room as tight as possible, opening up all 
spouts, spindles and other apparatus in which the moth or 
its larva is found. The chief obstacle here is the almost utter 
impossibility of making the large rooms air tight. Then, 
too, as evidenced by the testimony of a Pennsylvania miller 
a few years ago: "When placed in plates it does not evapo- 
rate quickly enough to produce the death atmosphere re- 
quired." This firm used three hundred soup plates half filled 
with bisulphide and distributed throughout the mill, besides 
saturating balls of cotton with the same and placing them in 
all reels and purifiers. The mill was left from Saturday 
night to Monday morning, and although thousands were 
found dead, many thousands more appeared from cracks and 
corners after a few days. 

SiilpJiiir: The burning of sulphur not practical, besides 
injuring the flour in sacks in the mills. 

Steam: Not practical, requiring too elaborate prepara- 
tion, and too frequent application; seriously injuiing grain 
or flour, and rusting machinery. 

Kerosene: Good for washing walls, machinery, floors, etc., 
where it cannot injure flour or grain. See reference to kero- 
sene on pages 15 and 16. 

Soliitioji of Soda and IVafer: Used strong for washing in- 
side of machines. 

Biihach, or Persian Insect Powder: Has been burned in a 
mill with only partial success, and expensive. 

Ammonia: Not successful. 

Hydrocyanic Acid Gas: Coming quite generallv into use. 
Placed in this list on account of danger of application unless 
in the hands of experienced parties. Deadly to all animal 
life. Prof. W. G. Johnson, author of "Fumigation Methods," 



THE MEDITERRANEAN FLOUR MOTH. 19 

says he has freed a number of mills of the Mediterranean 
Flour Moth by the use of this gas. 
Corrosive Sublimate: Not desirable. 

Lime: Whitewash to which a little glue has been added 
excellent for ceilings and walls ; the tendency to rub off can 
be stopped, it is said, by adding a handful of common salt, 
and a half teacupful of lard to each gallon of wash, which 
should be thoroughly strained before being used. 

Sulphuric Acid: Not recommended. 

Tobacco: Not particularly effective, either as smoke or 
infusion. 

Flour Paste: Compound of flour, water and vinegar and 
boiled by steam found to attract insects when paste was at a 
certain stage of fermentation. Moths fall into paste and 
perish. Too expensive, and has to be renewed every few 
days. 

Vinegar and Water: Not desirable. 

Molasses and Jl)iegar: Will attract and destroy some 
moths. 

"Tanglefoot" or Sticky Flypaper: Something like the sticky 
mixture used to coat Tanglefoot Fly paper can be made with- 
out much expense. Hundreds of moths have been caught in 
a single night on sticky fly paper. The paper should be 
placed in such places as are frequented by moths for egg 
laying, notably on piles of sacks filled with flour, etc. It 
is evident that if one can catch many female moths before 
egg laying, the process is well worth the expense incurred, 
and is a desirable measure. 

Coal Tor: Not desirable. 

Coal Tar and Vaseline: Better than coal tar alone. This 
and preceding used in the same manner as "Tanglefoot." 

Hand Picking: Not feasible. 

Hay Ropes: A German miller is the authority for the 
statement that ropes of new mown hay placed about the mill 
in coils afford attractive retreats for the moth. These coils 
were burned with the contained moths each week. 

High Temperature: Exposure to a temperature of 120 to 
130 degrees Fahr. for two or three hours is claimed to be fatal 



20 THE MEDITERRANEAN FLOUR MOTH. 

to the larva in the flour, and the same temperature for five 
or six consecutive hours is said to kill the eggs. This may 
prove of practical utility. 

Natural Enemies of the Flour Moth. 

Mr. Johnson describes in the American Miller for Novem- 
ber, 1895, the discovery of one parasite in America, Bracon 
hebetor, Say. In Europe Bracon brcvicornis and Chrcmyliis 
rubiginosus are mentioned as parasites. Poultry, seemingly 
fond of the "worm." has been kept in warehouses with some 
good efifect, though the hens appeared to tire of the diet. Mr. 
Johnson records the eating of a large number of pupae by a 
mouse, but no millers care to introduce mice into their mills 
for this purpose. Mice, as all entomologists know, readily 
eat insects, whether alive, or dead and pinned. 

Tribolimn confusmn, a little brown beetle, a common pest 
in flour mills, and discussed in this connection elsewhere in 
the report, has been known to devour the pupae of the flour 
moth. 

The so-called "bolting cloth beetle" (Tcncbroidcs iiiauritaii- 
icus) of California eats larva and pupa of flour moth and larva 
and adult of Triboliuiii. 

History of the Moth and Its Geographical Distribution. 

The origin of this pest cannot be stated definitely. It is 
probable that it always has been a widespread species, but 
not arousing attention until, attracted by flour and related 
products in mills, it changed its habits and became prominent 
as a menace to the flour milling industry. When first named 
by Zeller it was supposed by him to have been introduced from 
America, and it was so stated, but it was found by him in 
an inland town of Germany, Halle, before he knew of it at any 
seaport, and the same thing could be said of its first officially 
reported appearance in France. One miller has said with em- 
phasis that he knew of its occurrence in Paris as early as 1840, 
and another claims that it was in Constantinople in 1872, both 
statements, coming from different sources, affording addi- 
tional proof that it is not of American origin, where it was 



THE MEDITERRANEAN FLOUR MOTH. 21 

not officially reported until 1889 (Canada). There is evidence 
that it was in America a few years previous to this date, not 
however, until long after it was known in Europe. In 1885 
it was declared to be a dreaded pest in many Mediterranean 
ports, though no statement was made as to how long it had 
existed in those places. It is reported from Chili, from Mex- 
ico, New Mexico, from the island of Jamaica, and in 1890 
what was evidently this species was reported from South 
Africa. A practical miller who has since had experience with 
the pest in California, asserts that it was in Schleswig-Hol- 
stein, Germany, in 1858, although the first recorded observa- 
tion from Germany is in 1877. Freight cars and ships may 
easily be the means of carrying it. either as egg, worm or 
moth, to regions remote from the scene of its earlier appear- 
ance. 

It would be impossible to review in this publication the 
extensive literature upon this pest, nor is it necessary to list 
the bibliographical references. In order, however, to give an 
idea of its spread which is approximately correct, we list the 
following dates taken chiefly from Johnson's bibliographical 
list, and under each date insert the locality or localities 
where the moth appeared that year, as far as reported. In 
some instances, the outbreak may have been in the year 
preceding the report, but with these few exceptions, we be- 
lieve the dates are correct. 

1877. 
Outbreak at Halle, Germany. 

1879. 
Outbreak of 1877 referred to and insect named by Zeller. 

1884. 

Belgium. Supposed then to have been introduced in an 
American cereal. Reported also on lower Rhine. 

1885. 
Reported at Bremervorde, Germany. 



22 THE MEDITERRANEAN FLOUR MOTH. 

1886. 

Appeared in England. 

1887. 

London. Trieste. In the 39th Annual Report of New 
York State Museum of Natural History, J. A. Lintner pub- 
lishes his reply to an inquiry of the German consul general 
at New York City, asking for information about the Flour 
Moth. He states that he (Lintner) knew of no such insect 
in America. This is believed to be the first published state- 
ment in America regarding the pest. 

1888. 

T. D. A. Cockerell in the Entomologist for November, 
1888, page 779, declares that certain larvae found in flour 
which came from America may have come from infested 
Trieste flour in the same warehouses. 

1889. 

First report of its occurrence in North America, in Can- 
ada. May have been present a few years earlier. Reported 
as being in very destructive numbers in England. 

1890. 

Still present in England and spreading. A pest reported 
from South Africa which, from its habit, must have been this 
insect. 

189T. 

Reported in Venezuela (or a closely allied species). 

1892. 
California. Island of Jamaica. 

1893. 
On the increase in California. 



THE MEDITERRANEAN FLOUR MOTH. 



23 



1894. 

Still present in California. Reported from New York 
State, from North Carolina, and said to have been found in 
meal and bran from Mexico on exhibition in Chicago. 



1898. 

New York State. Pennsylvania. 
been present there for three years.) 
ada. 

1899. 

Wisconsin. 



(Reported as having 
New outbreak in Can- 



Wisconsin. 



Minnesota. 



1900. 



1901. 



1903. 
Minnesota. 

The Flour Moth is found in Illinois, in Colorado and other 
states ; it is, in fact, of very general distribution. 






Fig. 10.— Mediterranean Flour Moth: Ephcstia KuehnicUa, Zell. : a. larva; b, pupa; c, 
adult, enlarged; d. head and thoracic joints of larva; c, abdominal joint of sarne; 
still more enlarged; /, moth from side, resting; g. front wing, showing more im- 
portant markings; h, venation of fore wing; j. venation of hind wing, somewhat 
enlarged, (a, b, c and c, Riley & Howard in Insect Life; d, f, g, h and i, after 
Snellen.) 



24 



THE MEDITERRANEAN FLOUR MOTH. 



SOME OTHER INSECTS FOUND IN FLOUR MILLS 
OR AFFECTING STORED GRAIN. 



Many of the following" insects are also found in flour mills, 
and are frequently spoken of collectively as "weevils," which 
term is also sometimes, though not often, applied to the 
Mediterranean Flour Moth. That this is a wrong appellation 
is evinced by the fact that only two of the insects listed be- 
low are true weevils. Treatment which is successfully di- 
rected against the Flour Moth will kill any of the following 
insects, when occurring in the mill treated. 

The Granary Weevil. 




Fig. 11.— 0, b, c, different stages of the Granary Weevil (Calandria granaria), d, Rice 
Weevil (C. oryza).— F. H. Chittenden, Division of Entomology, U. S. Depart- 
ment of Agriculture. 



Fig. II illustrates this species and its congener, the Rice 
Weevil. The hair lines bv each show the natural size of the 



THE MEDITERRANEAN FLOUR MOTH. 



25 



insect. The female (jranary Weevil punctures a grain of 
wheat with her snout and lays an Qgg in the opening, the 
larva after hatching feeding upon the interior of the kernel. 
There may be from four to six broods of the Granary Weevil 
during the year, depending on the temperature. It is esti- 
mated that one pair, under favorable circumstances, will 
produce six thousand descendants in a year. This beetle is 
of a shining brown color. It cannot fly. Its cousin, the Rice 
Weevil, is a dull brown, its back provided with four reddish 
spots. It has well developed wings. In the southern states 
this latter weevil is a serious pest. 



The Angoumois Grain Moth. 




d "f 



Fig. 1-. — Angoumois Grain Moth, Sitolrnga ccrcalcUa: a, eggs; /'. larva at work; f, 
larva, side view: J, pupa; c. iiiotli; /, same, side view. — F. 11. Chittenden, Divi- 
sion of Entomology, V . S. Department of Agriculture. 



This pest is shown in Fig. 12. It is named from a prov- 
ince in France, where it has been known since 1736. It is 
claimed to have been found in America since 1728. More 
injurious in the South than in the North, it attacks not only 
wheat in the field and bin, but is partial to all the cereals. 
It is a brownish moth, resembling in a general way the 
Clothes Moth in size and apj^earance. 



20 



THE MEDITERRANEAN FLOUR I^IOTH. 



The Indian Meal Moth. 

This insect, resembHng somewhat 
the Mediterranean Flour Moth, not 
only feeds upon grain, flour, meal 
and bran in mills, but is seen in 
stores and elsewhere, where it af- 
fects spices, herbs, roots, seeds, dried 
fruit, etc. 

The larv?e or "worms" wdiich pro- 
duce these moths fasten together 
the kernels of grain, or the seeds or 
J:^-;'^:^i:tc:"^^r^l': Jil- -^ther material upon which they are 
Stf^fSar'va'^t^?^.o^ret feeding, with silkcu threads. These 
iecf I'iTe^'"^^ '"""' "''"'"'' '" ^"" masses, fouled with their excrement, 

greatly impair the value of tlie in- 
fested foodstuffs. It is said to have from four to six or uine 
broods amuially, depending upon the temperature of the rooms 
where it is found. It is shown in its various stages in Fig. 13. 

The Meal Snout Moth. 





Fig. 14. — I'yralis fari:uilis: a. ,'ulult moth; b, larva: c. pupa in cocoon, twice natural 
size.— F. H. Chittenden, Division Entomology, L'. S. Department of .Agricul- 
ture. 



This is a brownish moth, having darker brown patches 
at the outer edges of the front wings. Fig. 14 gives a very 
good, idea of its appearance ; the wavy white lines bordering 
the dark spots are characteristically striking. The larva 
makes tubes of silk, to which kernels of grain (if the worm 
is working in grain) adhere. (See Fig. 15.) Grain kept in 
dry and clean places is not likely to be affected. 



THE MEDITERRANEAN FLOUR MOTH. 



27 




Fig. 15. — Silken lubes covered witli wheat made by larvae of I'yralis fannalis, half 
natural size. — Lugger. 



The Confused Flour Beetle. 

The accompanying- figure (16) gives an excellent idea 
of this little pest, coninion enough in our flour mills. I'he 
beetle is dark br()\vn, and practically <)mniv<:)nnis, attacking. 




Fig. ll'i. — 1 riholiuii! confusiiiii: a, beetle; b, larva; c. pupa, all enlarged; d'. lateral lobe 
of abdomen of pupa; i', head of beetle showing antenna; /. same of 7'. fcrrugincum, 
all greatly enlarged.— F. H. Chittenden, Division of Entomology, U. -S. Depart- 
ment of Agriculture. 



according to Chittenden, flour, baking powder, red pepper, 
beans, peas, rice chaff, ginger, slippery elm, nuts and seeds 



28 



THE MEDITERRANEAN FLOUR MOTH. 



of various kinds. We have found it attacking dried insects 
in our cabinets. Like the other insects under discussion, a 
high temperature invites more rapid reproduction than when 
the temperature is low. It is said to attack and eat the larvae 
of the Mediterranean Flour Moth. 

The Slender-Horned Flour Beetle. 

This insect is more common in the south, but deserves 
a place here. Indian corn is its special food. The beetle is 
brown, having on its head between its eyes, two small pro- 
jections, readil}^ seen in the illustration. Fig. 17. The Broad- 





Fig. 17. — Echoceriis ma.villosns: a. larva; l>, pupa; c. adult male, all enlarged. — F. H. 
Chittenden, Division of Fntomology, U. S. Department of Agriculture. 



horned h'lour lieetle, and the Small-eyed Mour Ueetle should 
be added here ; the first more abundant on the Pacific coast, 
the second abundant and injurious in bakeries, feed stores 
and mills. 

The Yellow Meal Worm. 

This, F^ig. 18, is one of our more common pests in Indian 
meal and found in almost any mill products allowed to ac- 
cumulate in neglected places. The "worm" is round, smooth, 
waxen as to its surface, and nearly an inch long and yellow. 
The adult beetles fly and are attracted to ligh.ts. Another 
allied form common in America, but probably introduced from 



THE MEDITERRANEAN FLOUR MOTH. 



20 




Q):iX3::x:ccx:^ 



Fig. IS. — li'iicbno niolilor: a, larva; h, pupa; c, female beetle; (/. egg with surround- 
ing case; c-. antenna; a. b, c, d, about twice natural size; c. more enlarged. — Chit- 
tenden, Division of Entomology, U. S. Department of Agriculture. 

Europe or Asia, is the Dark Meal Worm. The Yellow Meal 
Worm or its beetle, or both, are said to make holes in b(^lting 
eloth. 

The Saw-Toothed Grain Beetle. 





Fig. 19. — Sil-'oiuis siiriiwiiu'iisis: a. adult beetle; b, pupa; f, larva._ all enlarged; d, 
antenna of larva, still more enlarged. — Chittenden, Division of luitomology U. S. 
Department of Agriculture. 



Very eommonly. though wrongly, called "weevil." It gets 
its name from the little teeth on each side of the thorax. (See 



30 



THE MEDITERRANEAN FLOUR MOTH. 



Fig. 19.) 'J he l)ectle is reddish brown, and frequently very 
common in grain, also, according to Chittenden, feeding in 
fiour. meal, dried fruits, seeds, breadstuffs, etc., and has been 
reported as having been found in starch, tobacco and dried 
meats. One or two other allied beetles we pass over as not 
beingf abundant enough to merit discussion here. 



The Cadelle. 





Fig. 20. — 7 cncbyoidrs maiiritaiiicus, Linn. : a, adult l)eetle with greatly enlarged antenna 
above; b, pupa; r, larva, all enlarged. — Chittentien, Divi-^iioti of Entomology, U. S. 
Department of Agriculture. 



Sometimes called "The Bolting Cloth Beetle," living upon 
grain, is blackish, one-third of an inch long, and comes from 
a fleshv, whitish larva with a brown head. (See Fig. 20.) 
Both beetle and larva attack and eat other grain or flour in- 
sects which are met with. They are, therefore, not an un- 
mixed evil. 



THE MEDITERRANEAN FLOUR MOTH. 31 

1 

ACKNOWLEDGMENTS. 

The two successful uiethods of conibatiu"" the Mediter- 
rauean Flour Moth iu uiills, frccciiig aud slrayiiig i^nth C. ^S"-, 
were told me in detail l)y practical millers who had resorted 
to these processes with happy results. To these parties my 
thanks are due and cheerfully given. I have not hesitated to 
use information contained in W. G. Johnson's article on "The 
Mediterranean Flour Moth (Ephcstia kiicliniclla, Zeller) in 
Europe and America,"" ])uhlished as an a])pendix to th.e 19th 
report of the state entomologist of Illinois, h^-om Farmers' 
Bulletin No. 45, Ignited States Department of Agriculture, 
"Some Insects Injurious to Stored Grain,"" by F. H. Chitten- 
den, statements were obtained bearing upon the habits 
and life histories of insects other than the Flour M(jth found 
in flour mills and elevators. A number of Chittenden"s illus- 
trations have also been used. 

The Booth Packing Company of Minneapolis very cour- 
teously allowed the use of their cold storage rooms in con- 
nection with experiments on the effects of dift'erent temper- 
atures on the pest under discussion. 

Acknowledgments are also due Director W. M. Liggett 
and yourself for recognizing the urgency of the situation, and 
enabling the Entomologist to place this information before 
the millers of the state quickly and in proper form. 

Respectfully, 

F. L. WASHBURN. 
State Entomologist. 

February 29th, 190^. 



LIBRftRY OF CONGRESS 



000 914 848 6 



